"no changes" in Finder?

OK so I have a buncha CDs full of stuff that I want to put on my new external hard drive.

I popped in a CD with four .avi files. It would only let me drag & drop 3 at a time into the external hard drive (no warnings, would only do three when I had four selected). It let me do whichever three I wanted, it wasn't just that the last one wouldn't drag & drop at all.

So I put the three in there, thinking when that was done it would let me put the fourth one in there.

It didn't.

Now whenever I put a CD with movies or pictures or files or anything into my drive, it won't let me drag & drop stuff on the desktop, or into the external hd.

I've messed with "ownership & permission" and "details" and all that jazz, but nothing is working.

I've noticed that on the bottom left of the finder icon it has the little "no changes" pencil with the line through it.

Is the "no changes" icon the problem? How would I get rid of it?

It's letting me drag things into iPhoto but that doesn't do me much good because it's only gonna work for the movies & photos and I'll have to wait for them to import, then wait again for them to transfer to the external hd.

It also won't let me repair permissions in disk utility.


EDIT: some of them are DVD+Rs if that makes a difference.

OK now I've realized that the "no changes" icon is also there when I try to download applications, meaning I can't download any new apps because it won't let me drag & drop it into my applications folder!


*EDIT- if the application downloads in a folder it works, but if it's in one of those "disk images" (I think that's what their called?) it doesn't.

any ideas?

http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh194.html (rather simplistic)
http://docs.info.apple.com/article.html?artnum=106237 (Long, kind of old)
http://docs.info.apple.com/article.html?artnum=106712 (Linked from above)